Material handlers of the type contemplated by the present invention are usually extremely large and complex, requiring significant investments in time, material, engineering and, of course, money. Such apparatus are normally associated with shiploaders, and particularly known as linear shiploaders or linear loaders. Such an apparatus is described in U.S. Pat. No. 3,856,159 issued to the inventor Dec. 24, 1974, and re-issued on Feb. 11, 1986 as U.S. Pat. No. Re. 32,081, the contents of both being incorporated herein by reference. The linear shiploader has become very popular and is used in a number of rather massive shiploading installations throughout the world today. Heretofore, all of the linear loaders incorporated a front pivot movably mounted on rails extending transversely of the bridge and substantially parallel to the vessel being loaded, and a fixed, rear pivot support which included means for permitting longitudinal movement of the bridge relative to said fixed pivot support. Such a construction, however, involved alternation in the direction of deflection under load of the rear part of the bridge, requiring special design attention. An alternative embodiment of the linear loader has been suggested in the aforementioned patents whereby the rear pivot support is not fixed but rather mounted on rails extending perpendicularly to the front end rails. However, as described in the aforementioned patents, such an embodiment creates particular difficulties in continuously feeding a conveyor mounted on the slewing bridge since there is no fixed pivot point at which to feed the bridge-mounted conveyor. For this reason, all existing installations, representing an installed base valued at several hundred million dollars, utilize stationary feeding and a fixed rear pivot support. An overview of these existing installations and the design criteria pertinent to each installation is described in an article by the inventor published in Bulk Solids Handling magazine, Vol. 11, No. 1, dated March, 1991.
The present invention is directed to solving the feeding problem for a linear loader having the alternate structure described above, namely a movable rear pivot support, and also at reducing the overall cost and dimensions of the bridge itself through a particular upwardly sloping configuration of the bridge-mounted conveyor proximate its feed point, which configuration could not be utilized in the previous loader designs due to the absence of a fixed feed point on the bridge-mounted conveyor.